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Passwd-file
===========

This file is compatible with a normal '/etc/passwd' file, and a password file
used by libpam-pwdfile <PAM> [PasswordDatabase.PAM.txt] plugin. It's in the
following format:

---%<-------------------------------------------------------------------------
user:password:uid:gid:(gecos):home:(shell):extra_fields
---%<-------------------------------------------------------------------------

For a password database it's enough to have only the user and password fields.
For a user database, you need to set also uid, gid and preferably also home
(see <VirtualUsers.txt>). (gecos) and (shell) fields are unused by Dovecot.

The password field can be in four formats:

 * 'password': Assume CRYPT <password scheme>
   [Authentication.PasswordSchemes.txt].
 * '{SCHEME}password': The password is in the given <scheme>
   [Authentication.PasswordSchemes.txt].
 * 'password[13]': libpam-passwd file compatible format for CRYPT <scheme>
   [Authentication.PasswordSchemes.txt].
 * 'password[34]': libpam-passwd file compatible format for MD5 <scheme>
   [Authentication.PasswordSchemes.txt].

extra_fields is a space-separated list of key=value pairs which can be used to
set various <passdb settings> [PasswordDatabase.ExtraFields.txt] and <userdb
settings> [UserDatabase.ExtraFields.txt]. Keys which begin with a 'userdb_'
prefix are used for userdb, others are used for passdb. So for example if you
wish to override <mail_location> [MailLocation.txt] setting for one user, use
'userdb_mail=mbox:~/mail'. <Variable> [Variables.txt] expansion is done for
extra_fields.

Empty lines and lines beginning with '#' character are ignored.

Multiple passwd files
---------------------

You can use all the <variables> [Variables.txt] in the passwd-file filenames,
for example:

---%<-------------------------------------------------------------------------
passdb {
  driver = passwd-file
  # Each domain has a separate passwd-file:
  args = /etc/auth/%d/passwd
}
---%<-------------------------------------------------------------------------

Passwd-file args
----------------

 * *scheme=<s>*: Allows you to specify the default <password scheme>
   [Authentication.PasswordSchemes.txt]. The default is CRYPT. This is
   available only for passdb.
 * *username_format=<s>*: Look up usernames using this format instead of the
   full username ('%u'). If you want to enable user@domain logins but have only
   "user" in the file, set this to '%n'.

Examples
--------

---%<-------------------------------------------------------------------------
passdb {
  driver = passwd-file
  args = scheme=plain-md5 username_format=%n /etc/imap.passwd
}
userdb {
  driver = passwd-file
  args = username_format=%n /etc/imap.passwd
  default_fields = uid=vmail gid=vmail home=/home/vmail/%u
}
---%<-------------------------------------------------------------------------

 * The default_fields is explained in <UserDatabase#Userdb_settings.>
   [UserDatabase.txt] They can be used to provide default userdb fields based
   on templates in case they're not specified for everyone in the passwd file.
   If you leave any of the standard userdb fields (uid, gid, home) empty, these
   defaults will be used.

This file can be used as a passdb:

---%<-------------------------------------------------------------------------
user:{plain}password
user2:{plain}password2
---%<-------------------------------------------------------------------------

passdb with extra fields:

---%<-------------------------------------------------------------------------
user:{plain}password::::::allow_nets=192.168.0.0/24
---%<-------------------------------------------------------------------------

This file can be used as both a passwd and a userdb:

---%<-------------------------------------------------------------------------
user:{plain}pass:1000:1000::/home/user::userdb_mail=maildir:~/Maildir
allow_nets=192.168.0.0/24
user2:{plain}pass2:1001:1001::/home/user2
---%<-------------------------------------------------------------------------

FreeBSD /etc/master.passwd as passdb and userdb
-----------------------------------------------

On FreeBSD, '/etc/passwd' doesn't work as a password database because the
password field is replaced by a '*'. '/etc/master.passwd' can be converted into
a format usable by passwd-file. As <PasswordDatabase.PAM.txt> can access the
system-wide credentials on FreeBSD, what follows is generally needed only if
the mail accounts are different from the system accounts.

If only using the result for 'name:password:uid:gid' and not using
<PasswordDatabase.ExtraFields.txt> you may be able to use the extract directly.
However, the Linux-style passwd file has fewer fields than that used by FreeBSD
and it will need to be edited if any fields past the first four are needed. In
particular, it will fail if used directly as a 'userdb' as the field used for
'home' is not in the same place as expected by the Dovecot parser. The
':class:change:expire' stanza in each line should be removed to be consistent
with the Linux-style format. While that stanza often is '::0:0' use of 'cut' is
likely much safer than 'sed' or other blind substitution.

In '/etc/master.passwd', a password of '*' indicates that password
authentication is disabled for that user and the token '*LOCKED*' prevents all
login authentication, so you might as well exclude those:

---%<-------------------------------------------------------------------------
# fgrep -v '*' /etc/master.passwd | cut -d : -f 1-4,8-10 >
/path/to/file-with-encrypted-passwords
# chmod 640 /path/to/file-with-encrypted-passwords
# chown root:dovecot /path/to/file-with-encrypted-passwords
---%<-------------------------------------------------------------------------

or permissions and ownership that may be more appropriate for your install and
security needs.

The following will work in many situations, after disabling the inclusion of
other 'userdb' and 'passdb' sections

---%<-------------------------------------------------------------------------
passdb {
  driver = passwd-file
  args = username_format=%n /path/to/file-with-encrypted-passwords
}
userdb {
  driver = passwd-file
  args = username_format=%n /path/to/file-with-encrypted-passwords
}
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2019-06-19 12:42)